Loud-speaker



March 5, 1929. a. E. COLBURN 7 1,704,460

LOUD SPEAKER Filed Jan. 8, 1927 2 Sheets-Sheet 1 March 5, 1929.

B. E. COLBURN LOUD SPEAKER Filed Jan. 1927 2 Sheets-Sheet 2 Maw;

Patented Mar. 5, 1929.

UNITED STATES PATENT OFFICE.

BEARL E. COLBURN, OF GREEN BAY, WISCONSIN, ASSIGNOR TO SUPER-BALL ANTENNA 60., OF GREEN BAY, WISCONSIN.

LOUD-SPEAKER.

Application filed January 8, 1927.

This invention relates to loud speakers, such for example, as those used on radio equipment.

bjects of this invention are to provide a novel form of loud speaker which is so constructed that a very long air column is providod between the speaker unit and the main sound chamber, and to so construct the differout parts of the device that vibration of the speaker or horn itself is stopped, so that there is no gradual building up of the vibration of the horn body itself from the speaking unit to the sound chamber.

More specifically, objects of this invention are to provide a loud speaker in which the air column is defined by means of a non-metallic curved horn opening into a metallic and relatively heavy sound distribution chamber which, in turn, opens into a larger, main sound chamber, such main sound chamber being formed of non-metallic material.

Further objects are to provide a loud speaker in which the main sound chamber is provided with an auxiliary chamber which operates not only as an auxiliary chamber, but also as a baflle plate to cause a more uniform distribution of the low notes in the main sound chamber.

Further objects are to provide a device having the characteristics noted above, which is so constructed that although the air column is very long, that nevertheless the device itself is compact and is a self-contained unit. An embodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a front view of the speaker with the base is section;

Figure 2 is a transverse sectional view;

Figure 3 is a view from the underside of the speaker with the base plate removed.

Referring to the drawings, it will be seen that the speaker comprises a main sound chamber 1 which opens into a chamber 2.

This chamber is secured rigidly to the underside of the top portion 3 of the cabinet within which the major portion of the apparatus is contained. The lower portion of the cabinet is closed by a base plate 4. The speaker unit is indicated by the reference character 5 and is connected with the chamber 2 by means of a gradually enlarging hornlike member 6, thus providing a very long air column in conjunction with the main chamber. It is preferable to construct the main 55 sound chamber 1 and the portion 6 of hard Serial No. 159,823.

rubber, wood, or other non-metallic material, and to form the chamber 2 of a die-cast metal which is relatively heavy and has a different characteristic for sound transmission than the wood, rubber, or other non-metallic material composing the portions 1 and 6. Thus, any vibration set up in the body of the horn itself is stopped and is prevented from building up along the length of the horn due to the composite nature of the material forming the horn.

The main chamber 1 is semi-spherical in contour and gradually merges into the oval openin from the chamber 2, as may be seen from Figures 1 and 2. This chamber 2 has an upwardly slanting bottom, as shown in Figure 1, to guide the sound waves upwardly without any sharp change in direction of travel at any given point in the chamber 2.

Within the main sound chamber 1, an auxiliary sound chamber 7 is positioned and is also of semi-spherical contour adjacent its upper portion. Its lower portion, however, tapers, as shown in Figures 1 and 2, and is secured to the adjacent portion of the main chamber 1. This auxiliary chamber 7 consti tutes also a bafile plate for the sound waves and it will be noted that the spacing of the member 7 from the main chamber 1 gradually increases as the outer and upper edge of the main chamber is approached. This auxiliary chamber or bafile plate 7 is provided with openings 8 adjacent its lower portion, particularly adjacent the forwardly curving part 10. The material is punched out in the formation of these openings 8, and is turned down, as indicated at 9 in Figure 2.

The forward face or outer opening of the main chamber 1 carries an inwardly curving cap 11 which is provided with a plurality of vertical bars or grating members 12, thus defining openings, as indicated at 13 in Figure 1, and providing also an attractive finish for the device.

In operation, it has been found that the horn will not vibrate from one end to the other as so frequently happens with the usual types of horns. This is secured primarily through the position of the die metal chamber 2 between the non-metallic members 1 and 6, so that the horn is not composed from one end to the other of the same material.

It is to be noted further that the distribution secured by this arrangement is excellent, for as the sound waves leave the chamber 2 they pass upwardly some of them entering the small chamber 7 through the apertures 8, and others being reflected against the rear surface of the larger chamber .1, and thenceoutwardly into the room.

It is to be noted that the sound chamber is semi-spherical and has an oblong opening at its outer bottom edge. This opening is defined by the downwardly extending walls of the sound chamber, and these walls e:-:- tend downwardly below the main outline of the sound chamber.

It will be seen further that although a very long air column is provided that nevertheless the device is compact and is not top-heavy, but is so constructed that a very pleasing proportion is maintained throughout the entire structure.

It has been found that not only is the dis tribution very much improved over that secured with the ordinary loud speakers, but that also there is a remarkablefreedom from distortion secured by this device.

Although the invention has been described in considerable detail, such description is intended as illustrative rather than limiting as the invention may be variously embodied and as the scope of such invention is to be determined as claimed.

I claim: I

1. A loud speaker comprising a cabinet having a speaker unit therein, an elongated horn extending from said speaker unit and coiled around within said cabinet, a chamber communicating with said horn and located within said cabinet and having an upper oval opening, a main sound chamber communicating with said first mentioned chamberthrough said oval-shaped opening, said main sound chamber being semi-spherical, and an auxiliary sound chamber carried within said main sound chamber and secured thereto at its lower edge, said auxiliary sound chamber opening forwardly towards the mouth of said main sound chamber and having entrance openings directed downwardly towards said first mentioned chamber.

2. An acoustic device comprising a main semi-spherical sound chamber having an oblong opening at the outer bottom portion thereof, an auxiliary sound chamber mounted Within the main sound chamber'and having a semi-spherical upper portion tapering and curving downwardly and having a transverse opening in the downwardly curving portion located above the said oblong opening of said main sound chamber.

In testimony that I claim the foregoing I have hereunto set my hand at Green Bay, in the county of Brown and State of Wisconsin.

BEARL E. COLBURN. 

